Patent Literature 1 discloses a pipe joint coupling apparatus having one pipe joint member (socket S) mounted on a support member (securing plate 22) of a device to be connected. The support member is supported by a flange 20 formed on the outer peripheral surface of the one pipe joint member and a collar 23. In addition, an elastic member (O-ring 21) is disposed in an accommodating groove (circumferential groove 26) formed on the outer peripheral surface of the one pipe joint member to elastically retain the one pipe joint member with respect to the support member.    Patent Literature 1: Japanese Utility Model Registration Application Publication No. Hei 7-38881